In response to mounting concerns regarding the decline in birthrate in Japan and the increasing aged population, center-based daycare has assumed an important role in Japanese society. In order to tackle the issues of low birthrate and longevity, demand for policies that encourage women to both participate in the workforce and have children is greater than ever. Since 1997, this perceived need has brought about a policy transformation in Japan's postwar system of approved nursery centers (i.e., nursery facilities that meet the national daycare quality standards), which had--until then--operated measures entirely under the control of the municipalities, as part of the child welfare policy of the Japanese government. In order to respond to the urgent need for daycare services and facilities, the government has instigated a policy of privatization throughout its nursery centers system and has relaxed many of the regulations in the field of daycare services provision. However, in the course of the privatization of public nursery centers, the government has been widely regarded as prioritizing "capacity (quantity)" concerns over "quality" concerns when constructing its policies. Because the nursery centers system has undergone legal reform and because quality concerns are on the rise, both researchers and administrative officers have come to recognize how important it is to define and measure quality nursery daycare. With this issue in mind, this study proposes an approach to assess the quality of Japan's nursery daycare against international standards, particularly from the standpoint of a state party's obligations under the 1989 United Nations Convention on the Rights of the Child (UNCRC). The following research questions are central to this study: To what extent does Japan comply with international standards on daycare quality? Are there international standards that Japan should be permitted exemptions from, and if exemptions are appropriate, what is the rationale for such exemptions? This study is the first detailed examination of Japan's nursery daycare policies under the framework of the UNCRC written in English. The introduction of a daycare quality assessment method to Japan--one that is based on international standards--serves as a useful basis both for the smooth formulation and implementation of nursery policies that ensure daycare provisions (in terms of quantity and quality) and to provide a benchmark against which reasonable judicial rulings can be made on the basis of the "the best interests of the child, " one of the core principles in the UNCRC. Furthermore, it will also help provide some insights into how stakeholders of nursery daycare in OECD countries are able to ensure that daycare quality takes children's best interests into account while also considering the historic, cultural, and social contexts of respective countries.